The present invention relates generally to the field of magnetic data storage, and more specifically to extending the useful life of magnetic tape cartridges exhibiting certain wear characteristics.
Some conventional tape drives adopt a linear recording system (a recording scheme that defines data tracks extending in parallel with the tape direction of travel) where data is simultaneously written to 32 tracks using 32 respectively corresponding heads. Each track is divided into 160 wraps with the corresponding writing areas slightly offset from one another.
Accurate tracking performance of the magnetic heads is necessary for writing data quickly, accurately, and densely onto this narrow track. Minor sideways displacement of the traveling tape relative to the heads takes the heads out of position relative to the data track, which may lead to data errors. Two servo bands sandwich each data band to enable accurate positioning of the magnetic heads for writing and reading of the data, and the servo bands provide information for obtaining the tape speed and the position of the head in the vertical direction (that is, in the across-the-tape direction).
Fine-tuned control in the track-following direction (control for positioning the head accurately on the track) makes use of a position error signal (PES) as an input for the track-following control system. The PES is the difference between a reference value (YPOS-reference) and track-following position information called YPOS (Y-Position) obtained by reading servo patterns written on the tape medium.